Sheryl Sandberg, Richard Branson, and 17 other successful people share their best career advice for people in their 20s

If clichés like “follow your passion,” “give 110%,” and “be true to yourself” just aren’t cutting it for you anymore, we’ve got some fresh takes on how to get a head start on your career.

From “don’t work too hard” to “relax,” here are some of the best — and oftentimes unconventional — pieces of advice for people in their 20s from some super-successful people:

Sheryl Sandberg: There is no straight path to where you are going.

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Sheryl Sandberg.

'As Pattie Sellers of Fortune Magazine says, careers are not ladders but jungle gyms,' the Facebook COO wrote on Quora. 'You don't have to have it all figured out.'

Sheryl Sandberg recommends having a long-term, abstract dream to work towards in addition to a more concrete 18-month plan. The long-term plan allows you to dream big while the short-term plan forces you to push yourself and think about how you want to get better over the next year and a half.

'Ask yourself how you can improve and what you're afraid to do,' she said, adding 'that's usually the thing you should try.'

Warren Buffett: Exercise humility and restraint.

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Warren Buffett.

In a 2010 interview with Yahoo, Berkshire Hathaway CEO said the best advice he ever received was from Berkshire Hathaway board-of-directors member Thomas Murphy. He told Buffett:

'Never forget Warren, you can tell a guy to go to hell tomorrow -- you don't give up the right. So just keep your mouth shut today, and see if you feel the same way tomorrow.'

During this year's Berkshire Hathaway annual shareholders meeting, Buffett also told a curious seventh-grader that the key to making friends and getting along with coworkers is learning to change your behaviour as you mature by emulating those you admire and adopting the qualities they possess.

Richard Branson: Never look back in regret -- move on to the next thing.

'The amount of time people waste dwelling on failures, rather than putting that energy into another project, always amazes me,' the billionaire Virgin Group founder and chairman told The Good Entrepreneur. 'I have fun running ALL the Virgin businesses -- so a setback is never a bad experience, just a learning curve.'

Yeah, we're always talking about following your passion, but we're all part of the flow of history … you've got to put something back into the flow of history that's going to help your community, help other people … so that 20, 30, 40 years from now … people will say, this person didn't just have a passion, he cared about making something that other people could benefit from.

J.K. Rowling: Embrace failure.

'I don't think we talk about failure enough,' Rowling told Matt Lauer on NBC's 'Today' show. 'It would have really helped to have someone who had had a measure of success come say to me, 'You will fail. That's inevitable. It's what you do with it.''

Melanie Whelan: Get a job, any job.

'Get a job and work hard,' she told The New York Times' Adam Bryant in an interview. 'You are going to learn a ton in whatever that job is, so don't stress too much about what it is or where it is. Just take a job and put your head down, work hard, raise your hand for anything anybody asks you to do.'

Melanie Whelan said it's important for young job seekers to live in the present rather than worry so much about where they're headed. The key is working as hard and learning as much as possible. When you do this, she said, good things will follow.

'A lot of people think in terms of 'should' -- I 'should' be a banker, I 'should' go to law school, I 'should' pursue what I studied in school.' This is a mistake, she told Bryant.

'A wise teacher from India shared this insight: The elephant keeps walking as the dogs keep barking,' she wrote.

'The sad fact is that we all have to navigate our way around the dogs in our career: external critics, competitors, horrible bosses, or colleagues who undermine. Based on my experience, I would advise you to prepare for the yapping to increase along with your success.'

'Some people will know exactly what they want to do at a very young age, but the odds are low,' he said. 'I feel like people in their early- to mid-20s are very earnest. They're very serious, and they want to feel like they have accomplished a lot at a very young age rather than just trying to figure stuff out. So I try to push them toward a more experimental attitude.'

Arianna Huffington: Don't work too hard.

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Arianna Huffington.

In a 2014 LinkedIn, The Huffington Post president and editor-in-chief revealed that she's often asked if young people pursuing their dreams should burn the candle at both ends.

'This couldn't be less true,' she writes. 'And for far too long, we have been operating under a collective delusion that burning out is the necessary price for achieving success.'

She says she wishes she could go back and tell her younger self, 'Arianna, your performance will actually improve if you can commit to not only working hard but also unplugging, recharging, and renewing yourself.'

George Stephanopoulos: Relax.

'Down the road, don't be afraid to take a pay cut to follow your passion. But do stash a few bucks in a 401(k) now,' the journalist said.

Marla Malcolm Beck: Remember that you won't end up where you start.

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Marla Malcolm Beck.

Malcolm Beck, CEO of Bluemercury, said in an interview with Adam Bryant of The New York Times that she always reminds students that 'nobody ends up in the first job they choose out of college, so just find something that is interesting to you, because you tend to excel at things you're interested in. But just go do it. You have nothing to lose.'

Her other piece of advice: Go into tech. 'If you look at all the skill sets companies need, they involve a comfort level with technology,' she told Bryant.

T.J. Miller: Work harder than anyone else around you.

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T.J. Miller.

The comedian and star of HBO's 'Silicon Valley,' told personal finance website NerdWallet that working harder than everyone around you is truly the formula to success. 'It worked for me, and I have mediocre talent and a horse jaw.'

'As a new hire, you will likely find yourself in tons of new situations, and it's up to you to figure out how to navigate them,' she wrote in an article for Business Insider.

'Remember that your manager is strapped for time, so know when to ask questions. Are you unsure of the objectives for an assignment? Asking her to clarify is crucial, since it's pretty hard to make the mark if you don't know where it even lies.

'On the flip side, avoid bombarding your manager with petty questions that could be answered by your peers or a quick Google search.'

Salli Setta: Never eat lunch alone.

The benefit of always having lunch plans with someone are two-fold: You can get information that will help you 'think about your job differently,' and you also get on your companion's radar.

'It isn't about saying 'hi, what are we going to talk about, let's talk about sports,'' Setta says. 'It's about identifying the object of this lunch in your mind' and going in armed with 'a couple of things that you want to ask, and a couple of things you want to share.'

Brian Chesky: Don't listen to your parents.

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Brian Chesky.

Chesky, CEO of Airbnb, said in an interview with The New York Times' Adam Bryant that recent grads shouldn't listen to their parents.

'They're the most important relationships in your life, but you should never take your parents' career advice, and I'm using parents as a proxy for all the pressures in the world,' he told Bryant. 'I also say that whatever career you're in, assume it's going to be a massive failure. That way, you're not making decisions based on success, money, and career. You're only making it based on doing what you love.'

Diane von Furstenberg: Keep it real.

'In order to trust yourself, you have to have a relationship with yourself,' she told Bryant. 'In order to have a relationship with yourself, you have to be hard on yourself, and not be delusional.'

Rick Goings: Be nice to everyone.

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Rick Goings.

Goings, CEO of home-products company Tupperware Brands, shared his favourite pearls of wisdom for young people with Business Insider. One of them was be nice to everyone when you go on a job interview.

'I like to check with the driver, our receptionist, and my assistants on how the candidate interacted with them. How you treat others means the world!'

Rachel Zoe: Never act entitled.

In a recent LinkedIn post, the famous celebrity stylist and editor-in-chief ofThe Zoe Report said her
biggest piece of advice for anyone starting his or her first job would be 'to make sure to never act entitled.'

She continued: 'It's important that no matter what your situation is, you work like you have only $5 in the bank.'

Mark Cuban: Be optimistic from the moment you wake up.

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Mark Cuban.

Cuban wrote a blog post in June 2009 -- which he included in his book 'How to Win at the Sport of Business' -- meant to inspire young people trying to establish their careers in a world that had been ravaged by the Great Recession, Business Insider's Rich Feloni reports. 'The economy has significantly improved since then, but the lessons Cuban drew from his own experience are just as valid.'

His advice? Live cheaply, take chances, find a job you love, be the best you can be, and, perhaps most importantly, be optimistic from the moment you wake up.

'You are going to screw up,' Cuban writes. But he says we all need to learn to let the little things go and see our failures as learning experiences.